Semiconductor integrated circuits wafers are produced by a plurality of processes in a wafer fabrication facility (fab). These processes, and associated fabrication tools, may include thermal oxidation, diffusion, ion implantation, RTP (rapid thermal processing), CVD (chemical vapor deposition), PVD (physical vapor deposition), epitaxy, etch, and photolithography. During the fabrication stages, products (e.g., semiconductor wafers) are monitored and controlled for quality and yield using metrology tools. As the feature sizes of integrated circuits are reduced, the amount of monitoring and controlling may need to be increased. This, however, increases costs by the increased quantity of metrology tools required, the increased manpower to perform the monitoring and controlling, and the associated delay in manufacturing cycle time.
Accordingly, a virtual metrology model is utilized for the production control and other purposes with reduced cost. However, the existing virtual metrology model takes intensive manpower for analyzing and checking each parameter/step, which is time consuming. In addition, some key parameters/steps can be missed due to wrong judgment, resulting in non-precise and misleading predictions. The associated wafer variations cannot be predicted by the existing method and the existing virtual metrology model.
Therefore, what is needed is a system and method for increasing the monitoring, controlling, and/or otherwise predicting device parameters, quality, and/or yield of products.